VSS Stopping During Program Execution

RDU

I'm running Retrospect 7.5 for Vista on Vista Ultimate. I received an error
message informing me that VSS did not operate correctly during execution &
the backup was not completed. The Windows Event Viewer indeed notes that the
VSS service entered the stopped state. The MS TechNet referral from EV noted
that "The %1 service entered the %2 state." and that this is a normal
operation. How can I stop the VSS service from stopping during backup
operations? Thanks.